Determination of hepatitis B virus genotypes by DNA sequence analysis in patients from ankara, Turkey

Hepatit B virusu (HBV) genotiplerinin dünya üzerindeki dağılımı coğrafi bölgelere göre farklılık göstermektedir. Ülkemizde yapılan çalışmalarda belirlenen HBV genotipi ise genotip D olup, homojen ve tek tip şeklinde yayılım saptanmaktadır. Bu çalışmanın amacı, Ankara’da Gazi Üniversitesi Hastanesine başvuran HBV enfeksiyonlu hastalarda HBV genotiplerinin belirlenmesidir. Çalışmaya, tümü HBsAg pozitif ve anti-HBs negatif olan 84 (52 erkek, 32 kadın) hasta örneği dahil edilmiştir. Hastaların %95.2’sinde anti-HBc, %47.6’sında HBeAg, %11.9’unda ise anti-HBe belirteçleri pozitif olup, HBV-DNA düzeyleri ortalama 5.7 x 107 ± 4.6 x 107 IU/ml; ALT değerleri ortalama 131 ± 171 IU/ml ve AST değerleri ortalama 98 ± 170 IU/ml olarak saptanmıştır. Örneklerden HBV-DNA ekstraksiyonu, fenokloroform yöntemi ile yapılmış, HBV-DNA S gen bölgesi polimeraz zincir reaksiyonu (PCR) ile amplifiye edilmiştir. PCR ürünlerinin döngüsel dizi analizi reaksiyonu; dideoksi zincir sonlanması yöntemine dayalı olan ticari bir kit (Cy5/5.5 Dye Primer Cycle Sequencing Kit; Visible Genetics, Kanada) kullanılarak gerçekleştirilmiştir. Elde edilen DNA dizileri floresans temelli otomatik bir DNA dizileme sisteminde (Long-Read Tower System, Visible Genetics, Kanada) okutulmuş ve analiz edilmiştir. Gen bankasından alınan yayınlanmış tüm genotiplerin S gen bölgesine ait DNA dizileriyle, hasta örneklerinden elde edilen DNA dizilerinin karşılaştırılarak değerlendirilmesi sonucunda, 84 örneğin tümünün (%100) HBV D genotipi ve ayw alttipi ile ilişkili olduğu görülmüştür. PHYLIP filogenetik analiz paket programı kullanılarak yapılan analiz sonucunda oluşturulan filogenetik ağaçlarda, çalışılan örneklerin D genotipine ait grupta kümelendiği izlenmiştir. Sonuç olarak, ülkemizdeki HBV suşlarının moleküler epidemiyolojisi ve ülkemizin içinde bulunduğu coğrafi konum ile uyumlu olarak, hastanemize başvuran hasta grubunda da başlıca genotipin D olduğu saptanmış ve HBV genotip tayininin, klinik yaklaşımların daha bilinçli olmasına olanak sağlayacağı düşünülmüştür.Hepatitis B virus (HBV) genotypes vary depending on the geographical region. The HBV genotype determined in Turkey has been genotype D which is found as the homogenously disseminated single genotype. The aim of this study was to determine HBV genotypes in a group of HBV infected patients who were admitted to a university hospital in Ankara, Turkey. Serum samples from HBsAg positive and anti-HBs negative 84 (52 male, 32 female) patients with HBV infection were included into the study. Anti-HBc was positive in 95.2%, HBeAg was positive in 47.6% and anti-HBe was positive in 11.9% of the patients. Mean HBV-DNA levels of the patients were 5.7 x 107 ± 4.6 x 107 IU/ml; mean ALT levels were 131 ± 171 IU/ml and mean AST levels were 98 ± 170 IU/ml. HBV-DNA was extracted from serum by the phenol-chloroform method and PCR was performed to amplify the S gene region of HBV-DNA. Cycle sequencing of PCR products was performed by a commercial “Cy5/Cy5.5 Dye Primer Cycle Sequencing Kit” (Visible Genetics, Canada) based on dideoxy chain termination method. The sequences were read and analyzed in an automated fluorescence-based DNA-sequencing system (Long-Read Tower System, Visible Genetics, Canada). The nucleotide sequences of the patient samples were compared with the previously reported sequences in gene bank for each genotype. According to the comparative analysis of S-sequences of all patient samples with the published sequences of the genotypes in gene bank, all of the 84 hepatitis B strains (100%) were shown to be related to D genotypic group, subtype ayw. A phylogenetic analysis was performed and phylogenetic trees were constructed using programs in the PHYLIP phylogeny inference package. The patient samples clustered within the genotypic group D. According to these results, the main HBV genotype in our patients was genotype D in accordance with the previous molecular epidemiologic information on HBV in this geographic area. HBV genotype determination may help to establish more rational clinical approach in the evaluation of HBV infected patients

Solvent Compatibility of Parylene C Film Layer

Parylene C has been preferred in various microfluidic and packaging applications as a chemical barrier; therefore, its durability in chemicals is critical to maintain functionality of the devices. In this paper, we investigated solvent compatibility of Parylene C in a range of solvents with regard to swelling of it and the change in its surface roughness at room temperature. The results of Parylene C swelling were associated with solubility parameter, delta (cal/cm(3))(1/2), which is predicted from the parameters of dispersion, polar, and hydrogen-bonding forces. Solvents that swelled Parylene C film layer mostly were benzene, chloroform, trichloroethylene, and toluene, while methanol, 2-propanol, ethylene glycol, and water did not cause any swelling. Subsequently, the adverse effects of diffusion of solvents through a Parylene C film layer were demonstrated by stripping of the encapsulated photoresist. In addition, a comparison was made between Parylene C and poly(dimethyl) siloxane (PDMS) considering the data of swelling ratios obtained from the experimental findings and the literature, respectively. Experimental findings showed that Parylene C is much more compatible to solvents than PDMS in high-throughput microfluidic and packaging applications. These results will be of great value to scientists for understanding compatibility of any selected solvent on Parylene C in the applications of micro devices. [2013-0113

AmpC Beta-Lactamase Expression Levels of Pseudomonas aeruginosa Isolates with Different Resistance Phenotypes

Pseudomonas aeruginosa üyelerinde Enterobacteriaceae ailesinin çeşitli türlerinde bulunan kromozomal kaynaklı AmpC’ye benzer indüklenebilen bir AmpC sef alosporinaz bulunduğu bilinmektedir. AmpC üretimi anlamlı derecede arttığında, P.aeruginosa karbapenemler hariç bütün ?-laktamlara direnç geliştirir. Bu çalışmada f arklı direnç f enotiplerindeki P.aeruginosa izolatlarının AmpC ekspresyon düzeyleri ve AmpC ?-laktamaz enziminin dirence etkisinin araştırılması amaçlanmıştır. Çalışmaya dahil edilen 49 P.aeruginosa klinik izolatının antibiyotik duyarlılık testleri disk dif üzyon yöntemi ile yapılmış ve CLSI önerileri doğrultusunda değerlendirilmiştir. Minimal inhibitor konsantrasyonları otomatize VITEK 2 sistemi (bioMerieux, Fransa) kullanı- larak belirlenmiştir. İzolatlar dört f arklı gruba ayrılmıştır: 1. Grup, çoklu ilaç dirençli (ÇİD) (sef tazidim ?64 µg/ml, piperasilin ?128 µg/ml, imipenem ?16 µg/ml ve gentamisin ?16 µg/ml); 2. Grup, izole karbapenem dirençli (İKR) (imipenem ?16 µg/ml); 3. Grup, hem karbapenem hem de kinolon dirençli (imipenem ?16 µg/ml, siprof loksasin ?4 µg/ml) ve 4. Grup, izole kinolon dirençli (siprof loksasin ?4 µg/ml) izolatlar. AmpC bölgesinin transkripsiyon ürün seviyesi gerçek zamanlı polimerize zincir reaksiyonu (qPCR) yöntemiyle LightCycler cihazı (Roche, Almanya) kullanılarak belirlenmiştir. Çalışmamızda incelenen 49 P. aeruginosa klinik izolatının 23’ünde (% 47) AmpC aşırı ekspresyonu tespit edilmiştir. Grup 1, 2, 3 ve 4 için ortalama ekspresyon değerleri sırasıyla 3717.66±4344.20, 6.96±13.52, 1.26±1.31 ve 0.54±0.30 olarak belirlenmiştir. Aşırı ekspresyon gösteren suşların 21’i (% 91) ÇİD izolatları içeren birinci grupta görülmüş ve diğer gruplarla karşılaştırıldığında birinci grubun istatistiksel olarak anlamlı f arklılık gösterdiği saptanmıştır (p=0.001). İKR izolatların ikisinde (% 22) aşırı ekspresyon tespit edilmiştir. Üçüncü ve 4. grupta ise AmpC aşırı üretimi görülmemiştir. AmpC aşırı üretimi P. aeruginosa’nın karbapenem direncine tek başına etki etmemekte, ilave direnç mekanizmaları birlikteliğinde dirence katkı sağlayabilmektedir. ÇİD ve İKR izolatlarının AmpC ekspresyon düzeyleri karşılaştırıldığında; ?-laktamaza daha dirençli gibi görünen karbapenemlerin antipsödomonal olarak kullanımı önerilebilir. Ayrıca kinolon dirençli 3. ve 4. grupta AmpC aşırı üretimi saptanma- mış olması AmpC ?-laktamazın kinolon direnci üzerine etkisiz olduğunu düşündürmektedir. AmpC ?-laktamaz direnci ile mücadelede yeni tedavi stratejileri geliştirilmeli ve AmpC gen bölgesinin ekspresyonunu düzenleyen mekanizmaların açıklanmasına yönelik moleküler çalış- malar planlanmalıdır.seudomonas aeruginosa carries an inducible AmpC cephalosporinase that is similar to the chromosomally encoded AmpC f ound in several members of Enterobacteriaceae. When AmpC production is signif icantly increased, P. aeruginosa develops resistance to all β-lactams excluding carbapenems. In this study, we investigated the expression level of AmpC and the eff ect of the AmpC β-lactamase enzyme on resis- tance among clinical isolates of P.aeruginosa with diff erent resistance phenotypes. The antibiotic sensitivity tests of 49 clinical isolates of P. aeruginosa included in this study were carried out using the disk diff usion method and evaluated in terms of the CLSI recommendations. VITEK 2 automated system (bioMerieux, France) was used to determine the minimum inhibitory concentrations. Four diff erent types of P. aeruginosa isolates were included in the study: Group 1, multidrug-resistant (MDR) isolates (cef tazidime ≥64 µg/ml, piperacillin ≥128 µg/ml, imipenem ≥16 µg/ml, and gentamicin ≥16 µg/ml); Group 2, one carbapenem-resistant (ICR) one (imipenem ≥16 µg/ml); Group 3, carbapenem- and quinolone-resistant isolates (imipenem ≥16 µg/ml, ciprof loxacin ≥4 µg/ml); and Group 4, one quinolone-resistant isolates (ciprof loxacin ≥4 µg/ml). The transcription product level of AmpC was detected by real-time poly- merase chain reaction (qPCR) using a LightCycler instrument (Roche Diagnostics, Germany). Among the 49 clinical P. aeruginosa isolates in our study, AmpC overexpression was detected in 23 (47 %) isolates. The mean exp- ression values in Groups 1, 2, 3, and 4 were 3717.66±4344.20, 6.96±13.52, 1.26±1.31, and 0.54±0.30, respectively. Twenty-one of 23 ove- rexpressed isolates was detected in Group 1, showing a statistically signif icant diff erence f rom the other groups (p = 0.001). Overexpression was detected in two of the nine ICR isolates (22 %). We did not determine AmpC overexpression in Groups 3 and 4. AmpC overproduction alone does not signif icantly alter the susceptibility of P.aeruginosa to carbapenems, but could certainly contribute to resistance if accompanied by additional resistance mechanisms. Comparison of AmpC expression levels between the MDR and ICR isolates indicated that carbapenems seem to be more resistant to β-lactamases and may show potential as an antipseudomonal β-lactam agent. In addition, the lack of AmpC overexpression in the quinolone-resistant isolates of Groups 3 and 4 suggests ineff ectiveness of AmpC β-lactamase toward quinolone resistance. New therapeutic strategies must be developed against AmpC β-lactamase resistance, and molecular studies should be planned to elucidate the mechanisms that regulate expression of the AmpC gene

Evaluation of Enterococcus Isolates Isolated in Three Years Period at Zonguldak Karaelmas University Hospital

The aim of the study was to identify Enterococcus isolates to species level from various samples obtained at Zonguldak Karaelmas University, Research and Application Hospital Clinical Microbiology Laboratory, between January 2002 and April 2005 and to evaluate their antimicrobial resistance profile. A total of 222 isolates were investigated. One hundred and eighteen isolates were identified at species level by using API 20 Strep identification system. Kirby-Bauer disc diffusion method was used for the determination of penicillin, streptomycin, gentamicin, vancomycin and teicoplanin susceptibility. Streptomycin 300 µg and gentamicin 120 µg discs were used to determine high-level resistance to aminoglycosides. Seventy-seven of the 115 isolates were identified as Enterococcus faecalis (67.3%), 31 as Enterococcus faecium (26.9%), three as Enterococcus casseliflavus (2.6%) and one as Enterococcus durans (0.9%). Three isolates couldn’t be identified (2.6%) with the mentioned system. Resistance to penicillin was 50% for the total isolates while it was 40.2% for E. faecalis and 70.9% for E. faecium strains. In all strains high-level resistance to aminoglycosides for streptomycin and gentamicin were 54.9% and 46.8%, respectively. Resistance to both streptomycin and gentamicin was determined in 21 of the total strains (9.4%). All strains were susceptible to vancomycin and teicoplanin. No beta-lactamase producing isolates were detected

The evaluation of antibiotic susceptibilities of pseudomonas aeruginosa isolates: Decreasing susceptibilities to various antibiotics

Hastanemizde Haziran 2005-Ocak 2010 arasında çeşitli klinik örneklerden izole edilen 570 Pseudomonas aeruginosa izolatının CLSI kriterlerine göre Kirby-Bauer disk difüzyon yöntemi ile belirlenen antibiyotik duyarlılıkları değerlendirilmiş ve sonuçlar, Ocak 2002-Haziran 2005 arasında yine hastanemizde izole edilen suşlara ait sonuçlar ile karşılaştırılmıştır. Son dönemde en yüksek duyarlılık oranları amikasin (% 78) ve tobramisin (% 77) için, en düşük oranlar ise aztreonam (% 57) ve siprofloksasin (% 56) için alınmıştır. 2005-2010 yıllarında izole edilen suşlarda duyarlılık oranlarının, 2002-2005 yıllarındaki suşlara göre imipenem, sefepim, seftazidim, piperasilin-tazobaktam, amikasin ve siprofloksasin için anlamlı derecede (p<0.05-0.001) azaldığı belirlenmiştir. *Gülhane Mikrobiyoloji Günleri: Antimikrobik Kemoterapi: Laboratuvar Uygulamaları ve Yenilikler’de sunulmuştur.The susceptibilities of 570 Pseudomonas aeruginosa isolates obtained from various clinical samples in our hospital between June 2005 and January 2010 were determined by Kirby-Bauer disk diffusion method according to the guidelines of the CLSI. The results were compared with those reported from the same hospital for isolates obtained between January 2002 and June 2005. The recent results revealed that susceptibilities of the isolates to amikacin (78 %) and tobramicin (77 %) were highest while susceptibilities to aztreonam (57 %) and ciprofloxacin (56 %) were lowest. The susceptibility rates of isolates obtained between 2005-2010 were significantly lower for imipenem, cefepime, ceftazidime, piperacillin-tazobactam, amikacin ve ciprofloxacin when compared to those reported between 2002-2005 (p<0.05-0.001)

Determination of the enzyme types in extended spectrum beta-lactamase (ESBL) producing Klebsiella pneumoniae and Klebsiella oxytoca strains by isoelectric focusing

Bu çalışmada hastanemizde Ocak 2002-Aralık 2004 tarihleri arasında izole edilen GSBL üreten 56 Klebsiella suşunda betalaktamaz tiplerinin izoelektrik odaklama yöntemi ile belirlenmesi amaçlanmıştır. İncelenen bakterilerin çoğunda (%62.5) izoelektrik odaklama yöntemi ile birden fazla enzim varlığı gözlenmiştir. Her iki Klebsiella türünden elde edilen enzimler için en sık belirlenen izoelektrik noktalar (pI) 7.6, 7.2, 8.4 olmuştur. Bunu sırasıyla pI 8.6, 8.2, 5.6, 7.0, 7.8, 8.0, 5.4, 8.3, 8.8, 9.0, 5.9 ve 6.8 izlemiştir. Kökenlerde belirlenen izoelektrik noktalara göre öngörülen SHV enzim tipleri, SHV-3 ve benzeri (pI 7.0), SHV-4 ve benzeri (pI 7.8), CTX-M enzim grubundan ise CTX-M-15 (pI 8.6), CTX-M-20 (pI 8.3) ve CTX-M-5 (pI 8.8) olmuştur. Kökenlerimizde TEM grubu enzimleriyle uyumlu olarak pI 5.4, 5.6 ve 5.9 izoelektrik noktaları belirlenmiştir. Değerlendirilen kökenlerde SHV ve CTX-M enzimlerinin daha sık olduğu sonucuna varılmıştır.The aim of this study was to determine the types of beta-lactamases by isoelectric focusing in the 56 ESBL producing Klebsiella strains isolated in our hospital between January 2002-December 2004. The presence of more than one enzyme (62.5%) was observed by isoelectric focusing in the majority of the analysed bacteria. The most commonly designated pI points for the enzymes obtained from both Klebsiella species were 7.6, 7.2 and 8.4. Consecutive pI points were 8.6, 8.2, 5.6, 7.0, 7.8, 8.0, 5.4, 8.3, 8.8, 9.0, 5.9 and 6.8 in order of frequency. With regard to the isoelectric points determined in the strains, the anticipated SHV enzyme types were SHV-3, SHV-3-like enzymes (pI 7.0), SHV-4, SHV-4-like enzymes (pI 7.8) and the CTX-M type enzymes were CTX-M-15 (pI 8.6), CTX-M-20 (pI 8.3) and CTX-M-5 (pI 8.8). The isoelectric points 5.4, 5.6 and 5.9 were determined with concordance to the TEM group enzymes. It is concluded that SHV and CTX-M enzymes were the most common enzymes among the bacteria analysed

Effects of Solvents on Dissolution of Photoresist in Parylene Microchannels

This paper presents a study for the effects of different types of solvents on dissolution of photo resist inside the parylene micro channels. Theoretical and experimental studies were carried out to model the dynamic behavior of the dissolution. In this account, dissolution rate expressions were derived by taking into account the reaction of resist with the solvent. Micro channels with a cross section of 15 mu m x 50 mu m were fabricated by encapsulating photo resist inside the parylene layers and using glass wafer as substrate. Experimental results indicated that photo resist dissolution in dipolar aprotic solvents was much faster than the other types of solvents. This finding can be used to select alternative chemicals for stripping encapsulated photo resist

The Evaluation of Resistance Genes and Gene Mutations in Quinolone Resistant Escherichia coli and Klebsiella spp. Isolates

Amaç: Bu çalışmada, bölgemizdeki Escherichia coli ve Klebsiella spp. izolatlarında kinolon direnç sıklığının belirlenmesi, bu izolatlarda sık görülen kinolon direnç mekanizmalarının varlığının araştırılması amaçlanmıştır.Gereç ve Yöntem: Şubat-Ağustos 2009 tarihleri arasında izole edilen nalidiksik asite dirençli/orta duyarlı bulunan 265 Escherichia coli, 33 Klebsiella pneumoniae ve 2 Klebsiella oxytoca izolatında qnrA, qnrB, qnrS, aac(6')-Ib, gyrA ve parC gen bölgelerinin araştırılması polimeraz zincir reaksiyonu yöntemiyle yapılmıştır. gyrA ve parC gen bölgelerindeki mutasyonların saptanması için dizi analizi yapılmıştır.Bulgular: Nalidiksik asit direnci E. coli için % 52, Klebsiella spp. için % 27.5 olarak belirlenmiştir. Nalidiksik aside dirençli izolatlarda beta-laktam, aminoglikozit, trimetoprim-sülfometoksazole direncinin ve GSBL üretiminin anlamlı olarak daha yüksek olduğu belirlenmiştir. gyrA için kinolon direncini tanımlayan bölgede (Ala67-Gln106) çift mutasyon olduğu, bunların Ser83Leu ve bir izolat dışında Asp87Asn, tek izolatta ise Asp87Tyr şeklinde olduğu belirlenmiştir. parC için dizileme yapılan izolatların hepsinde Ser80Ile değişimi olduğu gözlenmiş, izolatların 32'sinde (% 40,3) ilave bir mutasyon bulunduğu ve bunların 26 izolatta Glu84Val, 4 izolatta Glu84Gly, 2 izolatta ise Glu84Ala olduğu belirlenmiştir. E. coli izolatlarının 99'unda (% 37,4), K. pneumoniae izolatlarının dördünde (% 12,1) aac(6')-Ib geni belirlenmiştir. İncelenen izolatlarda qnr geni bulunmamıştır.Sonuç: İzolatlarımızda kinolon direnci ve GSBL üretimi yüksek bulunmuştur. Kinolon dirençli izolatlarımızda gyrA ve parC bölgelerinde üç ve daha fazla mutasyonun bulunduğu ilave olarak aac(6')-Ib'nin belirgin olarak direnç mekanizmasına eşlik ettiği belirlenmiştir. İzolatlarımızda qnr belirlenmemiştirObjective: The aims of this study are to detect the quinolone resistance rates among Escherichia coli and Klebsiella pneumoniae spp. isolates in our region and to investigate the most common quinolone resistance mechanisms. Material and Methods: The presence of qnrA, qnrB, qnrS, aac(6’)-Ib, gyrA and parC genes were investigated by polymerase chain reaction method in 265 Escherichia coli, 33 Klebsiella pneumoniae and two Klebsiella oxytoca strains which were isolated between February–August 2009, and found to be non/intermediate susceptible to nalidixic acid . Sequence analysis was used for detection of gyrA and parC mutations. Results: Resistance to nalidixic acid was determined as 52% for E. coli and 27.5% for Klebsiella spp. Beta-lactam, aminoglycoside, trimethoprim-sulfamethoxazole resistance and ESBL-production rates were significantly higher among nalidixic acid resistant isolates. Double mutations were detected in gyrA quinolone resistance defining region (Ala67-Gln106); the first one being Ser83Leu in all isolates and the other being Asp87Tyr in one isolate and Asp87Asn in other isolates. Ser80Ile alteration was observed among all isolates sequenced for parC mutations; while 32 (40.3%) of the isolates had an additional mutation, as Glu84Val, Glu84Gly and Glu84Ala in 26, four and two, respectively. The aac(6’)-Ib gene was detected in 99 (37.4%) of E. coli and four (12.1%) of K. pneumoniae isolates. The qnr gene was not detected in any of the tested isolates. Conclusion: The quinolone resistance rates and accompanying ESBL-production was high among the isolates in our region. We have detected three or more mutations in gyrA and parC regions in quinolone resistant isolates, and additional aac(6’)- Ib gene in a significant number of isolates. The qnr gene was not detected in any of the tested isolates

Evaluation of reduced susceptibility to vancomycin among MRSA strains isolated from clinical specimens

In this study, a total of 390 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens between April 2004 and June 2008, in a university hospital in Zonguldak (located at Black Sea region), Turkey, were evaluated retrospectively for reduced susceptibility to vancomycin. Brain heart infusion (BHI) plates containing 4 and 6 &micro;g/ml of vancomycin were used to screen for vancomycin intermediate S.aureus (VISA) strains. Additionally, vancomycin minimal inhibitory concentrations (MIC) of the isolates were determined by agar dilution method. No growth was observed on the screen plates after 24 and 48 hours of incubation. None of the isolates revealed MIC values equal to or higher than 2 &micro;g/ml; MIC90 and MIC50 values were 1 &micro;g/ml. Although VISA isolates were not detected in this study, no data was obtained for heterogeneous VISA isolates since macro-E test or population analysis were not performed. It was concluded that systematic surveillance of MRSA isolates is of particular importance to investigate the presence of VISA/hVISA isolates which may lead to treatment failures and hospital epidemics.In this study, a total of 390 methicillin-resistant Staphylococcus aureus (MRSA) strains isolated from clinical specimens between April 2004 and June 2008, in a university hospital in Zonguldak (located at Black Sea region), Turkey, were evaluated retrospectively for reduced susceptibility to vancomycin. Brain heart infusion (BHI) plates containing 4 and 6 &micro;g/ml of vancomycin were used to screen for vancomycin intermediate S.aureus (VISA) strains. Additionally, vancomycin minimal inhibitory concentrations (MIC) of the isolates were determined by agar dilution method. No growth was observed on the screen plates after 24 and 48 hours of incubation. None of the isolates revealed MIC values equal to or higher than 2 &micro;g/ml; MIC90 and MIC50 values were 1 &micro;g/ml. Although VISA isolates were not detected in this study, no data was obtained for heterogeneous VISA isolates since macro-E test or population analysis were not performed. It was concluded that systematic surveillance of MRSA isolates is of particular importance to investigate the presence of VISA/hVISA isolates which may lead to treatment failures and hospital epidemics